Re: Does SMP work at all on 40x ?

[Christophe Leroy]

Le 30/01/2019 à 12:43, Michael Ellerman a écrit :
Christophe Leroy <christophe.le...@c-s.fr> writes:

In transfer_to_handler() (entry_32.S), we have:

#if defined(CONFIG_40x) || defined(CONFIG_BOOKE)
...
#ifdef CONFIG_SMP
        CURRENT_THREAD_INFO(r9, r1)
        lwz     r9,TI_CPU(r9)
        slwi    r9,r9,3
        add     r11,r11,r9
#endif
#endif

When running this piece of code, MMU translation is off. But r9 contains
the virtual addr of current_thread_info, so unless I miss something,
this cannot work on the 40x, can it ?

On CONFIG_BOOKE it works because phys addr = virt addr

AFAIK 40x can't be SMP:

   config SMP
        depends on PPC_BOOK3S || PPC_BOOK3E || FSL_BOOKE || PPC_47x


But this stuff is all before my time.

The commit that added the SMP block was clearly only meant for BookE:

   4eaddb4d7ec3 ("[POWERPC] Make Book-E debug handling SMP safe")

Ok, then no need to worry about it. It will implicitely get fixed with 
the THREAD_INFO_IN_TASK_STRUCT series.

Christophe